Casting, such as investment casting, involves feeding a molten material through one or more sprues to fill one or more mold cavities. For single crystal castings, the mold is then slowly withdrawn from a furnace to solidify the material from the bottom of the mold. A grain starter block is arranged at the bottom of the mold to solidify the molten material with a preferred grain orientation. The grain starter block can include a grain selector for preferentially growing a single crystal microstructure. As the molten material cools, a solidification front moves from the bottom of the mold toward the top of the mold. In investment casting, the mold is then removed, leaving a cast work piece. The sprues and excess gating are then cut off from the component.